Revert "Revert "Bugfix: allSettled is not registered when finally is missing (#127)""

This reverts commit e83b46e.

Author: taylorhakes

src/polyfill.js

@@ -25,8 +25,11 @@ var globalNS = (function() {
 // https://github.com/taylorhakes/promise-polyfill/issues/114
 if (typeof globalNS['Promise'] !== 'function') {
   globalNS['Promise'] = Promise;
-} else if (!globalNS.Promise.prototype['finally']) {
-  globalNS.Promise.prototype['finally'] = promiseFinally;
-} else if (!globalNS.Promise.allSettled) {
-  globalNS.Promise.allSettled = allSettled;
+} else {
+  if (!globalNS.Promise.prototype['finally']) {
+    globalNS.Promise.prototype['finally'] = promiseFinally;
+  } 
+  if (!globalNS.Promise.allSettled) {
+    globalNS.Promise.allSettled = allSettled;
+  }
 }